BeaverBeads Streptavidin Magnetic Beads, 300 nm

Product Overview

BeaverBeads™ Streptavidin at 300 nm are superparamagnetic microspheres with streptavidin covalently coupled to the bead surface. The streptavidin–biotin interaction has a dissociation constant of about 10⁻¹⁵ M, among the strongest non-covalent bonds in biology, which makes it the standard way to capture anything that can be biotinylated: antibodies, antigens, oligonucleotides, proteins and peptides.

At 300 nm this is the sub-micron member of the family. The very high surface-area-to-volume ratio gives it the highest oligonucleotide capacity in the range, and the particles stay suspended long enough for near-homogeneous binding kinetics rather than the settling behaviour of larger beads.

Binding capacity at 300 nm

Biotinylated single-stranded oligonucleotide (24 nt): ≥450 pmol per mg of beads — the highest in the BeaverBeads Streptavidin range, matched only by the 1 µm bead. Biotinylated IgG: ≥15 µg per mg of beads. Supplied at 10 mg/mL.

The trade-off is separation speed. Sub-micron superparamagnetic particles respond more slowly to the same magnetic field than micron beads, so every separation step takes longer. If your workflow is dominated by wash cycles rather than by capacity, the 2 µm bead (Cat. 22305) is usually the better choice.

Applications

Nucleic acid work. The high oligonucleotide capacity makes this the size of choice for isolating nucleic acids, preparing nucleic acid probes, and hybridisation capture of DNA and RNA with biotinylated probes.

Protein–nucleic acid interaction. Biotinylated DNA or RNA fragments immobilised on the beads are used to pull down and identify the proteins that bind them.

Immunoassay and chemiluminescence. Used as the solid phase in magnetic particle chemiluminescence immunoassay (CLIA) and ELISA. The manufacturer's manual gives a complete CLIA protocol using 50 µL of beads per well of a 96-well plate with 15-minute incubations at 37 °C.

Also used for immunoprecipitation, cell sorting and phage display screening.

Coupling your biotinylated ligand

The manufacturer's procedure washes the beads three times, then incubates them with the biotinylated antibody or protein at a bead concentration of 1 mg/mL for 30 minutes at room temperature on a rotating mixer, followed by five washes. The full protocol is in the user manual under Documents.

Handling and safety

Do not freeze or dry the beads. Vortex for about 20 seconds to a uniform suspension before every use — sub-micron beads settle during storage. Allow extra time on the magnetic separator and confirm the supernatant is clear before discarding it. The preservative contains ProClin-300 and BSA; if either interferes with your assay, wash the beads into your own buffer before starting. Keep beads and separators away from metal objects, electronic devices and implanted electronic devices such as cardiac pacemakers.

For Research Use Only. Not for use in diagnostic or therapeutic procedures. Specifications are those published by the manufacturer, BEAVER Biomedical Engineering Co., Ltd.